Add action to set start from video position

Closes #148

TODO.md

@@ -1,4 +1,5 @@
 Gaupol 1.7.1/1.8
 ================
 
+* [x] Add action set start from video position (#148)
 * [x] Add and fix English spell-check special cases

data/ui/menubar.ui

@@ -104,6 +104,10 @@
             </item>
           </section>
         </submenu>
+        <item>
+          <attribute name="label" translatable="yes">Set St_art From Video Position</attribute>
+          <attribute name="action">win.set-start-from-video-position</attribute>
+        </item>
         <item>
           <attribute name="label" translatable="yes">Set En_d From Video Position</attribute>
           <attribute name="action">win.set-end-from-video-position</attribute>

gaupol/actions/edit.py

@@ -174,6 +174,17 @@ def _affirm_doable(self, application, page, selected_rows):
         aeidon.util.affirm(application.player.ready)
         aeidon.util.affirm(len(selected_rows) == 1)
 
+class SetStartFromVideoPositionAction(gaupol.Action):
+    def __init__(self):
+        gaupol.Action.__init__(self, "set-start-from-video-position")
+        self.accelerators = ["U"]
+        self.action_group = "unsafe"
+    def _affirm_doable(self, application, page, selected_rows):
+        aeidon.util.affirm(page is not None)
+        aeidon.util.affirm(application.player is not None)
+        aeidon.util.affirm(application.player.ready)
+        aeidon.util.affirm(len(selected_rows) == 1)
+
 class SplitSubtitleAction(gaupol.Action):
     def __init__(self):
         gaupol.Action.__init__(self, "split-subtitle")

gaupol/agents/edit.py

@@ -271,6 +271,16 @@ def _on_set_end_from_video_position_activate(self, *args):
         if pos is None: return
         page.project.set_end(row, pos)
 
+    @aeidon.deco.export
+    def _on_set_start_from_video_position_activate(self, *args):
+        """Set subtitle start from video position."""
+        page = self.get_current_page()
+        mode = aeidon.modes.SECONDS
+        row = page.view.get_selected_rows()[0]
+        pos = self.player.get_position(mode)
+        if pos is None: return
+        page.project.set_start(row, pos)
+
     @aeidon.deco.export
     def _on_split_subtitle_activate(self, *args):
         """Split the selected subtitle."""